Good, J&S, Gledhill, Vokera Bad, Worcester(arrogant f**ks), Baxi(waiting, clueless)
but I think it all depends on who you get on the day. I may use a tech line maybe once a month tops. i hear a lot of bad about Ideal tech but last few times ive called them they've been ok. I often find the smaller rubbish manufacturers have the better tech guys